8 ounces uncooked = 2 cups dry = 4 cups cooked for "short goods," such as elbow macaroni, shells, rotini (corkscrews), ruote (wagon wheels), penne or mostaccioli (quills), cut ziti, and other small to medium shapes
8 ounces uncooked = 2 cups dry = 2-1/2 cups for egg noodles
8 ounces uncooked = a 1-1/2-inch-diameter bunch = 4 cups cooked for "long goods," including spaghetti, cappellini, fettuccine, vermicelli, and linguine
Since it's impossible to put long, uncooked spaghetti in a measuring cup, here is a handy way to measure. To make 2 cups of cooked spaghetti, use 4 ounces of dried spaghetti. If you don't have a scale, hold dried spaghetti together in a bunch. A 4-ounce portion of 10-inch-long spaghetti generally has a diameter of about 1 inch.
You can, however, use a measuring cup for short pasta such as noodles or macaroni. To make 2 cups of cooked noodles, measure 2 cups (4 ounces) of dried medium noodles.